id	keyword
american_scientific_journal-8173	smoking
american_scientific_journal-8173	study
american_scientific_journal-8173	health
american_scientific_journal-8173	participants
american_scientific_journal-8173	smokers
american_scientific_journal-8173	years
american_scientific_journal-8173	gingival
american_scientific_journal-8173	tobacco
american_scientific_journal-8173	teeth